Tables, Charts, and Graphs

Tables, charts, and graphs are useful in determining patterns of change over time, particularly with respect to aspects of economic and social history. Your textbook almost certainly contains information on population, industrial and/or farm production, slavery, the makeup of the labor force, and immigration presented in this manner. Here are some hints on handling questions based on statistical data:

• Read the title and both the horizontal and vertical axis on a chart or graph carefully so that you understand what information is given.

• Pay particular attention to the date range. A significant event, for example, war or depression, may explain the changes shown.

• The numbers may be presented in absolute terms or in percentages. Absolute numbers are often rounded off or abbreviated. If the title of a table, for example, includes the phrase (in thousands), the number 48,000 is really 48 million.

Example 1

The simplest way to present statistical data is in a table. The most direct question requires an interpretation of the information and does not necessarily require any specific knowledge of American history.

IMMIGRATION TO THE UNITED STATES 1820-1860 BY COUNTRY OF ORIGIN

Source: U.S. Bureau of the Census, Historical Statistics of the United States from Colonial Times to 1970.

1. According to the table shown above, the greatest numerical increase in immigration was from

A. Asia between 1850 and 1860

B. Ireland between 1830 and 1840

C. Ireland between 1840 and 1850

D. Germany between 1830 and 1840

E. Germany between 1840 and 1850

The correct answer is C. Immigration from Ireland between 1840 and 1850 increased from just over 39,000 to 164.000, a far larger increase than that of any other country listed. The same table could be used to test your factual knowledge about immigration before the Civil War. Here’s an example:

1. The significant increase in emigration from Ireland between 1840 and 1850 was mainly due to

A. opportunities for unskilled workers in U.S. factories

B. the passage of the Homestead Act

C. the effects of the Irish potato famine

D. the British policy of settling English farmers on Irish lands

E. religious oppression against the Catholic Church in Ireland

The correct answer is C. The failure of the Irish potato crop in 1845 led to widespread famine and emigration from the country.

Example 2

The line graph is useful to show trends over time. The horizontal axis is usually the time line, and the vertical axis is the subject of the graph. In the sample given below, the subject is energy sales expressed in millions of kilowatt-hours.

ELECTRICAL ENERGY IN LOS ANGELES 1970-1980

Source: Los Angeles Department of Water and Power.

2. While the trend of increasing energy sales in Los Angeles continued during the 1970s, the accompanying graph shows a sharp decline in actual consumption during the period. The decline was most likely due to

A. a sharp rate increase to residential customers

B. conservation measures introduced in response to the Arab oil embargo

C. a decline in population

D. the effects of a serious recession

E. the closing of plants using fuel because of air-pollution restrictions

The correct answer is B. This question requires that you read the graph correctly and relate the statistical information to a particular event. The sharp decline began in late 1973 and continued into 1974, a period that coincides with the Arab oil embargo. By curtailing fuel oil supplies, the embargo forced many electric utilities and local governments to institute strict energy- conservation ordinances.

Example 3

The important thing to remember about the pie chart is that the circle represents one hundred percent and the portions, or slices, of the pie represent a smaller percentage. The AP exam usually bases a question on several pie charts so that you can see changes or make comparisons. The sample given below shows the results in the presidential elections in 1904, 1908, and 1912 by the percentages each candidate received.

PRESIDENTIAL ELECTION RESULTS

Source: U.S. Bureau of the Census, Historical Statistics of the United States from Colonial Times to 1970.

3. From the election results shown above, Wilson won the presidency in 1912 mainly because

A. voters supported his New Freedom program

B. the Republican vote was split between Teddy Roosevelt and Taft

C. Wilson won the southern states

D. Eugene Debs took votes away from Taft

E. support for the Prohibitionist candidate increased

The correct answer is B. Looking just at the popular vote, it seems likely that the Republicans would have won the election if the party had been unified behind a single candidate. Any votes that the Socialist Debs received wouldn’t have gone to the conservative Taft, and the South had been a traditional Democratic stronghold since Reconstruction.

Statistical data can often be presented in different formats. Here's an example of a bar graph that uses the popular vote in the elections of 1904, 1908, and 1912 that could be used to ask the same question posed above. Note that while bar graphs are usually on the vertical, the data are shown in this example on the horizontal.

PRESIDENTIAL ELECTION RESULTS